French police, Tottenham Hotspur officials and stewards were on the lookout for potential violence against UK fans in Lyon on Thursday, after three supporters were injured in what appeared to be an antisemitic attack on an English pub in the city.

The north London club said that three fans had suffered "minor injuries" in the incident on Wednesday night, when up to 50 masked thugs attacked the Smoking Dog pub, which was packed with Spurs supporters on the eve of their team's second leg Europa League tie with Olympique Lyonnais.

It is believed one fan suffered a broken arm during the incident.

Eyewitnesses said the attackers smashed doors, and threw cast-iron chairs, wooden objects and a flare in the pub, which is popular with expatriates. Witnesses also claimed they made Nazi salutes. Firefighters, police and, according to some reports, even Spurs officials were forced to intervene.

A club statement on Twitter said: "Club officials attended an incident last night in Lyon. A group of around 50 people confronted fans. The situation was dealt with and arrests were made within the hour. Three fans sustained minor injuries & received prompt medical assistance.

"Spurs officials and stewards will be in the city throughout the day, along with match-day French police ahead of kick-off."

A report published this week by the Jewish Community Protection Service (SPCJ) in France, said 22 antisemitic acts reported to the police in Lyon last year, the third worst for a French city after Paris and Marseille. Neighbouring Villeurbanne, part of the wider Lyon area also experienced 22 incidents, in what the SPCJ called "a year of unprecedented violence against Jews in France".

Christian Radnedge, a Spurs-supporting journalist who was in the Smoking Dog, told the BBC that it had been "full to the rafters" when there was "a huge cacophony of noise and the sound of glass being smashed". As supporters tried to get away "from a load of projectiles and a group of masked men trying to make their way into the pub", other fans tried to hold their attackers back "with tables and chairs and anything else they could get their hands on".

Radnedge said: "There was nothing to suggest they were Olympique Lyonnais fans. They were wearing masks and balaclavas."

The Smoking Dog's landlord, Dave Eales, originally from Nottinghamshire, said: "At 10.18 the pub was rammed with Tottenham fans watching the Champions League on the television. The front of the pub, which is made up of reinforced glass, was attacked by 20 to 25 people.

"They threw projectiles through the windows. There was a standoff. They didn't get into the bar. Then it calmed down," he said. "Then they came back a second time and it all started again.

"There were three injured Tottenham fans taken away by ambulance. One of them had a head injury. I'm not sure how bad it was."

One fan, who did not want to be named, said: "There were 50 who attacked in the first wave and 25 in the second. It's a pretty scary thing when you're confronted by people doing Nazi salutes.

"A lit flare was thrown through the window as well as the heavy weight, the kind that's used on terraces to hold down umbrellas … It was terrifying. I've never seen anything like it. They threw iron stools through the windows as well."

The French radio station RMC sport said Tottenham fans had probably been attacked because the club was "known for being Jewish".

The local newspaper Le Progrès quoted several witnesses saying that a gang of around 40 young French men described as skinheads had attacked the English supporters.

One bar owner told the paper: "All day we had been welcoming English supporters and everything was calm. Suddenly these people arrived and they began throwing stones and stools against our windows. They hurt some customers who were outside. I'm really shocked."

Another bar owner was quoted saying: "They were looking to provoke a fight. They started having a go at people who were just sitting there in peace."

He said the hooligans had returned twice to attack his bar.

Lyon fans are often labelled fachos or fascists by bloggers critical of their behaviour.

Spurs were allocated 2,700 tickets for the match, but it is not known how many fans travelled either in official club packages or independently. UK police always travel with the fans, to help in and around the stadium before, during and after the match.

Spurs won the first leg of tie 2-1 last week. Their fans regularly parade the club's Jewish credentials, chanting "Yid Army", "Yids" or "Yiddo". This has been criticised by the Society of Black Lawyers and others over what they regard as antisemitic language. The supporters, many of whom are not Jewish, have now taken to singing: "We'll sing what we want."